Container closure



Oct. 12, 1965 A. M. FISCHER 3,211,316

CONTAINER CLOSURE Original Filed Sept. 12, 1958 5 Sheets-Sheet l 23 J0JZ .J3 jg ATTORNEY Oct. l2, 1965 A. M. FISCHER 3,211,316

CONTAINER CLOSURE Original Filed Sept. l2, 1958 y 3 Sheets-Sheet 2 21e r2j V w llIIllIllIlIl/III/IllI//llIIIll/lIlIIll/ll A Y M15 Ja 245( ALBERTER ab 3' 13j) #XM-w ATTORNEY Oct. 12, 1965 A. M. FISCHER CONTAINERCLOSURE 5 Sheets-Sheet 3 Original Filed Sept. 12. 1958 y RH OC M mw MEF. T V T mM A T R E B A United States Patent 3,211,316 y yCONTAINERCLOSURE Albert M. Fischer, Dowa'giac, Mich., assighor, by mesneassignments, to Union Carbide Corporation, a corpog ration 'of New Yorkp p Y Y Original application Sept. 12, 195,8, Ser. No. 760,692, nowPatent No. 3,087,639, dated Apr. 30, 1963. Divided and this applicationApr. 25, 1963, Ser. No. 275,673

3 Claims. (Cl. 21S- 39) ThisV application is a division of applicationSerial No. 760,692, `tiled September l2, 1958, and now U.S. Patent3,087,639.

The present invention relates, in general, to closures such as crownclosures, metallic cap closures, screw-on closures and the like, and, inparticular, to a new and improved cap closure and plastic sealing meanstherefor, which can be assembled with substantially conventional crownassembling machines.

,Bottle caps, also referred to as crown closures, generally comprise ametallic crown cap, preferably formed of cold rolled tin plate, having acorrugated rim or skirt within which a sealing means is placed; thelatter usually being cemented or otherwise secured to the crown cap. Ofrecent innovation, in the crown 'closure industry, has been the use ofsealing means made of plastic, such as polyethylene. Further developmentof plastic sealing means to further increase their usefulness as crowncap sealing means, brought about the provision of marginal rings or rimsand flex-rings as well a's inner sealing rings, as for example, theplastic sealing means disclosed and claimed in the U.S. Patent No.2,829,790 to Alfons Isele- Aregger issued April 8, 1958 and entitledBottle Closures, and the application for U.S. patent of AlfonsIsele-Aregger, Serial No. 559,445, filed January 16, 1956, entitledSealing Disc for Metallic Cap Closures, Crown Closures and the Like,issued on August 25, 1959 as U.S. Patent 2,901,139, to which referenceis made for a full and complete description thereof.

However, some embodiments of prior art plastic sealing means could nottoo successfully 4be used in conventional crown assembling machinesbecause of their tendency to nest with each other i.e., the'interlocking of the respective annular marginal rims and seal ringswhen attacked in the seal feed tube in such machines. When such nestingtook place, the machines shuttle or ejector mechanism for ejecting wouldcause tearing of the seals and/ orfwould insert more than one seal invany one crown cap. On the other hand, those embodiments of Aprior artsealing means which did work reasonably successfully in crown assemblingmachines did not have good sealing qualities in use-very undesirablefeatures.

Still a-nother disadvantage in existing plastic sealing meansfor crowncaps is that they could not be positively retained in the crown capprior to the capping ope'ration, which was due chiefly to 4theinsuicient frictional retention characteristic between the marginal sealrim and the crown cap.

Accordingly, it is a general object of my invention to overcome the`general disadvantages found in vprior art closures.

Briefly, myiinvention comprises a sealing means of relatively thinmaterial, such as polyethylene `or other suitable plastic material,having an 4outer marginal peripheral ring or rim, an inner relativelythin flex-ring, and one or more inner sealing rings, which surrounds a'relatively thin diaphragm. In -some embodiments of my invention, theouter marginal ring -is thicker 'in median plan than the Ainner sealingrings, is preferably provided with a substantially flat top and bottomso as to form a substantially trapezoidal configuration, and the innerseal '3,211,316 Patented Oct. 12, 1965 ICC Ving rings are preferablyprovided with sides of al certain angularity with respect to each other.These features function as an anti-nesting measure in the crown assemblymachines as will be understood hereinafter, and the radially outerperiphery of the marginal ring is preferably pointed or provided with asharpv corner in median plan and is somewhat larger than the diameter ofthe inside of the metallic crown cap, whereby the marginal ring togetherwith the dex-ring will cooperate to be frictionally retained in thecrown cap as will be understood hereinafter. g

In other embodiments of my invention, wherein the outer marginal ringisomitted and the flex-ring is retained, the outer seal ring is thickerthan the inner seal ring or rings and provided with substantially datsurfaces to facilitate stacking as an anti-nesting 4measure in crownassembly machines as will be understood, and in all the embodiments ofmy invention, the outer marginal seal ing ring andthe inner sealing ringor rings are preferably symmetrical in median plan so as to facilitatetheir sorting in the hopper of conventional crown assembly machines inwhich the sealing means are normally placed.

With my new and improved sealing means, I( have found that I can use aminimum of plastic Ymaterial and a minimum of metal in the crown capitself by use of shorter skirts on the crown cap and by using thinnergauge metal. I have found also that with my sealing means, aluminum maybe used as well as conventional tin plate for crown caps.

As to the crown cap, where desirable or necessary in cert-ainapplications and as an added feature to my present invention, I providemy crown cap with a retaining means for positively retaining the sealingmeans therein. This retaining means for my crown cap comprises aplurality of inwardly extending projections, or an inwardly extendingperipheral band, which will cooperate with the radially outer peripheryof the marginal ring or the flex-ring, as the case may be, of my sealingmeans to positively retain the sealing means within the crown cap. Inone embodiment these projections or the band are formed of a specialfriction producing lacquer.

In certain other applications where the projections or bands are notdesired, I have provided still another Vmanner of retaining `the sealingmeans in the crown capjby the provision of means such as the addition ofsuitable quantities of bentonite, magnesium silicate, etc., to theconventional lacquer used to coat the inside of the crown cap. Thepurpose ofthe addition of this material -is to increase the AfrictionalYqualities of the coating, thus assuring an improved frictionallretention ofthe seal in the crown cap.

Another important feature of my invention is the provision of a new andimproved 'shuttle mechanism and a new and `improved seal feed tube forcrown assembly machines. The working edge of my shuttle mechanism has aconfiguration which conforms with the particular configuration of theperiphery of my sealing means and I have improved the seal feed 'tube ofconventional crown assembling machines to cooperate with :the stackingof the plastic sealing means, as will be explained in detailhereinafter. y

Thus, a more particular object of -my invention is 'to provide a new andimproved plastic sealing means for crown closures and the like.

Still `another object of my invention is to `provide a new and improvedplastic sealing means for crown closures and the like useable inconventional crown assembling machines now in general `use in the crownclosure producing industry, but having my new and improved seal feedtube and shuttle ejector mechanism.

Still another object of my invention is to provide a new and improvedplastic sealing means having improved frictional retentioncharacteristics in the crown cap.

Another object of my invention is a new and improved metallic crown capwhich will cooperate with my new and improved plastic sealing means toretain the plastic sealing means in the crown cap prior to the cappingoperation.

Still another object of my invention is to provide a new and improvedplastic sealing means and a new and improved metallic crown which can bemanufactured with a minimum of plastic material and which will provide ameans of reducing the metal required of the crown cap when made ofconventional tin plate, or the use of aluminum for the crown caps.

Still another and further object of my invention is the provision of anew and improved seal feed tube and a new and improved shuttle mechanismin conventional crown cap assembling machines which will cooperate withmy new and improved plastic sealing means.

Other and more particular objects of my invention will be apparent tothose skilled in the art from the following description and drawingsforming a part hereof and wherein:

FIG. 1 is a top plan view of a plastic sealing means, constructed inaccordance with the teachings of my invention, having an outer annularmarginal ring and inner annular seal rings of a vertical thickness lessthan the vertical thickness of the marginal ring;

FIG. 2 is a vertical, cross-sectional view of the plastic sealing meansshown in FIG. l;

FIG. 3 is a vertical, crosssectional view of the sealing means shown inFIGS. l and 2 and inserted in a crown cap, illustrating how my sealingmeans cooperates with a known form of an indentation for holding thesealing means positively in the caps, and resting on the top of a bottlelip prior to the crowning operation;

FIG. 4 is a vertical, cross-sectional view of the sealing means, crowncap and bottle lip, shown in FIG. 3, after the crowning operation;

FIG. 5 is a partial, vertical, cross-sectional view of a plastic sealingmeans, constructed in accordance with my invention, having an outerannular marginal ring and inner annular rings of various verticalthickness but less than the vertical thickness of the marginal ring;

FIG. 6 is a partial, vertical, cross-sectional View of plastic sealingmeans of a type similar to that shown in FIG. 5 but showing the outer ormarginal ring with a flat top and bottom portion similar to the marginalring of FIG. 2;

FIG. 7 is a partial, vertical, cross-sectional view of a plastic sealingmeans similar to that shown in FIG. 5 except that the inner annularsealing rings are vertically narrower than the outer annular marginalring but of the same vertical thickness as to each other, similar to thesealing means of FIG. 2;

FIG. 8 is a partial, vertical, cross-sectional view of my plasticsealing means having only one annular sealing ring of the same verticalthickness as the outer marginal ring;

FIG. 9 is a partial, cross-sectional View of my plastic sealing means,similar to that shown in FIG. 8 except that the outer marginal ring hasthe same vertical thickness as the inner sealing ring and is providedwith a flat top and bottom portion;

FIG. 10 is a partial, cross-sectional view of my plastic sealing means,similar to that shown in FIG. 8, except that the inner sealing ring hasa vertical thickness less than the vertical thickness of the marginalring;

FIG. 11 is a partial, vertical, cross-sectional view of my plasticsealing means, similar to the sealing means shown in FIG. 10, exceptthat the marginal ring is provided with a dat top and bottom portion;

FIG. 12 is a partial, vertical, cross-sectional view of another form ofmarginal ring for my sealing means;

FIG. 13 is a partial, vertical, cross-sectional view of my plasticsealing means in which the space between the outer marginal ring with aat top and bottom and the inner sealing rings is reduced to a minimum;

FIG. 14 is a partial, vertical, cross-sectional view of a conventionalcrown assembly machine ejector with my plastic sealing means positionedin the cylinder of the crown assembly machine;

FIG. 15 is a partial, vertical, cross-sectional view of another form ofmy plastic sealing means wherein the marginal ring is omitted, theex-ring extended, and the radially outer sealing ring is provided withflats to prevent nesting;

FIG. 16 is a vertical, cross-sectional view of one embodiment of a crowncap, constructed in accordance with the teachings of my invention,showing to advantage a peripheral rim formed in the metal of the cap topositively hold the sealing means in the cap prior to the crowningoperation;

FIG. 17 is a vertical, cross-sectional view of still another embodimentof my crown cap having another type of rim or band formed of improvedlacquer for positively retaining the sealing means in the crown cap;

FIG. 18 is a vertical, cross-sectional view of still another embodimentof a crown cap showing to advantage another form of projections or dotsformed of improved lacquer for retaining the sealing means positively inthe crown cap;

FIG. 19 is a partial, enlarged, plan view of a blank from which thecrown caps are blanked in a conventional manner and illustrating toadvantage the means of forming the lacquer retaining rim or band for thecrown cap as shown in FIG. 17;

FIG. 2O is a partial, enlarged, plan view of a blank, such asillustrated in FIG. 19, but showing to advantage the lacquer retainingprojections or dots for the crown cap as shown in FIG. 18; and

FIG. 21 is a vertical, cross-sectional view of the elements of the crownassembly machine for suitably adhering the sealing means to the crowncap in applications -where the use of adhesive is thought necessary.

Turning now to the drawings and in particular to the FIGS. 1 through 4,I have illustrated a plastic sealing means, indicated in its entirety as10, constructed in accordance with the teachings of my invention in itspreferred form which comprises a relatively thin imperforate disc havinga relatively thin diaphragm 11 in its central portion, adjoined by `orencircled by one or more annular seal rings 12, 13 (two shown) each ofwhich comprises axially or vertically extending ribs of triangularcrosssection terminating in not smaller than a right angle andpreferably an obtuse angle defined by sides 14, 15 and 16, 17,respectively, with the sides 15 and 17, facing the outer periphery ofthe sealing means, being provided with a Hatter incline than sides 14and 16 for a purpose hereafter to be described. Sealing rings 12 and 13are surrounded on their peripherally outer end with a relatively thin,flexible, membrane-like area or flex-ring 18, and which is provided togive the sealing means 10l the necessary flexibility in this area forthe purpose hereinafter to be described.

Adjoining the flex-ring 18 and encircled thereby, is an outer marginalring 20, which forms the outer periphery of the sealing means and in itspreferred form has a substantially flat top and the bottom side 21, 22.It is to be noted that my sealing means in its preferred form issymmetrical or substantially symmetrical in cross-section (or, otherwisestated, is symmetrical or substantially symmetrical in median plan), andthat the vertical thickness of the marginal ring 20 is greater than :thevertical thickness yof the seal rings 12, 13 to be advantageous for acrown assembling machine.

It can be appreciated that with the sealing means symmetrical incross-section, both sides are useable and, when a plurality of thesesealing means are disposed in a hopper for eventualA use by the crownassembly machine, any sorting that will otherwise be required if therewas non-symmetry, has been eliminated.

l While I have shown the marginal rin-g 20 as having a flat top andbottom with the sides, such as 21a and 2111, actually forming anglestherewith, as for example at 21C, with the'anglerZlic being delined bysides 21 and 21d (FIG. 12) whereby `side 21d is merely a curve with asuitable radius Ato blend the substantially ilat top with the sides; theimportant point being that the top and bottom sides are `substantiallyfiat so that the top will cooperate in a stacking manner with the bottomside of a like sealing means, such as illustrated in FIG. 14.

The outside diameter of the sealing means is preferred to be slightlylarger (at least 0.005 inch) than the standard inside diameterof a crownsuch as 23 so that it permits the seaLwhen pressed into the crown 23during the crown assembling operatiomto align itself, more or less, withthe contourrof the inside of the crown as more fully illustrated in FIG.3. In this position the Hex-ring 1,8 exercises a radial force againstthe inside of the crown skirt due Vto its tendency to straighten out,which force is transmitted to the louter edge 24 of the marginal ring20, which presses against the crown skirt thereby establishing thefrictional retention of the sealing means 10 in ,the crown 23.

This tendency of the seal 10 and especially the Hex-ring 18 tostraighten out has another advantage in the crown assembly operation. Itis a well known fact that very close when produced by injection moldingor other suitable methods, yet on the other hand, the crowns or capssuch as 23 (see FIGS. 3 and ,4) due to the wear of the blanking dies,may have slightly varying inside diameters deviating from standard. l

By, way of explanation of the operation of my seal means, the plasticmaterial selected must meet certain standards of the beverage, food anddrug industries and it also must have required physical properties i.e.,suincient tensile strength, elasticity, resiliency and a minimum of coldnow'. v While any suitable plastic materials may be employed, I` prefera low density polyethylene wherein, due to the `particular configurationof my sealing means, the resiliency of the polyethylene is -fullyutilized. While plastic materials, such as a low density polyethyleneare not `readily resilient and compressible in items having substantialIcross-sectional areas, it has been found that narrower cross-sectionalareas, such as employed in the sealing means of my invention, showremarkable resiliency as demonstrated by their compressibility,.provided their molecular structure is not overstrained. Due to thisresiliency, the sealing means is able to compensate for imperfections inthe bottle lip and also forthe difference inthe coefficients of thermalexpansion between glass a'nd steel as in the case of crowned bottles. Asoutlined herein, the degree of resiliency, and therefore, the ability toeffect 'a gas-tight seal, is directly related to the shape of thecross-section of the lri'ngs or rims of seals.

As illustrated in FIG. 4, the sealing veffect is obtained by compressingthe annular sealing rings 12, 13 and the marginal ring 20, of theVpreferred form of my invention, illustrated in FIG. 2, when the crowncap 23 is pressed on la bottle lip 25 of bottle 26 and the crown skirt27 is crimped onto a bottle locking ring 28. In this crowningoperation,` the sealing ribs 12, 13 are compressed and align themselveswith the ,contour of the bottle lip 25, and, as usual, in this typecrowning operation, the greatest pressureper square inch is appli-edrintheV areav30 of ,the bottlelip 25, however, with the configuration of mymarginal seal ring 20 it can be forced into the 'angular space 30awithout overstrain in the molecular structure of the plastic materialand thus the resiliency of this section is also retained. From theforegoing description it can be seen that the marginal seal ring of myinvention has two functions namely: V(l) to retain the seal in the crownvcap before crowning, and (2) to act as an additional sealing area; thislatter feature being very important in the function of the preferredembodiments of my invention, for example, Where bottle imperfections arefound. Too, t-he pressure necessary to effect a tight seal is not highenough to overstrain the molecular structure of` other parts of thesealing means participating in the sealing action and, therefore, allparts of the sealing means retain their resiliency resulting in agas-tight closure. I have found, under exhaustiveV tests on a crownclosure employing my invention, that the sealing ability was notimpaired when repeated temperature changes ranging from 33 F. to 150 F.were produced during an extended test period of Iseveral weeks. Thesetests also produced pressures which were quite high, viz., in a testwithrfive (5 volumes of gas, at an elevated temperature of F., apressure of lbs. per square inch is produced and it was found 'out that,with the i sealing means, such as described herein, pressures of 200lbs. per square inch were retained.

By way of explanation for the results of the tests on my sealing means,reference is made to FIG. 4 where it can be seen that the internalbottle pressure indicated as P in a bottle 26', tends to lift the crowncap 23. However, due to the configuration of the sealing means 1,0, thepressure does not act, as in the case of a cork seal or other sealingmeans, over the entire area of the sealing means, but only over the areadefined or circumscribed by the inside diameter of the innermost sealingring 12, which in one specific embodiment of my invention is about 0.70inch. Consequently, an internal bottle pressure of 315 lbs. per squareinch acting against such a seal, equals SL30 lbs. It can be seen that ifmy sealing means did not have the annular sealing ring 12 and woulddepend on the marginal seal ring 2t) only, the pressure acting againstthe crown would be 118.80 lbs. which is based on the seal outsidediameter of 1.060 inches.

The construction and operation of myseali'ng lmeans in the crown cap aspressed on the bottle 26 has still other additional advantages. It iswell known that a low density polyethylene is permeated by water vapors,CO2, etc., and, therefore, can normally onlybe used under specialconditions for the sealing of a vacuum or pressure packed liquidscontaining CO2 or other gases. According to my invention, a vseal madeof low density polyethylene is rendered effectively impermeable to gaseswhen the sealing rings are compressed in the sealing area as in FIG. 4.In this crowning operation, there is created a relatively high specificpressure in the narrow contact zones formed between the bottle lip 25and the seal ring 12, 13, the marginal ring 20 on V'one side and thecrown cap 23 on the other.

While I have explained the operation of my invention in connection withmy 4preferred form of sealing means, as illustrated in FIG. 2 of thedrawings, wherein the sealing rings 12 and 13 each have'the obtuse anglea, formed by sides 14, 15 and 16, 17 and have explained the operationthereof in connection with the marginal lsealing ring 20 of greatervertical or transverse thickness, it can be appreciated from a 'study ofFIG. 13, that vdifferent angles on the sealing rings may be employed.Furthermore, it is not necessary that two such sealing rings as 12 and13 be employed as illustrated in FIGS. 8, Y9 and 1'0 nor is it necessarythat the sealing rings have a thickness less than the marginal ring, asillustrated in FIGS. `8 and A9; the important point is that one of thesealing rings or the marginal ring should be thicker and preferably witha flat top and bottom side so as to permit stacking ofthe seals in aseal feed tube without nesting. Furthermore, in certain otherapplications, thefflex-ring 18 may be narrowed 'down toa minimum, asillustrated in FIG. 13,'or the marginal =ring itself maybe eliminated asillustrated in FIG. 15 leaving only an extended and modified flexringwith flat sides 13a and 13b being provided on the relative thick sealring 13. Also, while it is preferred that the marginal ring betrapezoidal and have flat top and bottom surfaces, such as illustratedin FIGS. 2, 6, 9, 11, 12 and 13 for the prevention of nesting in a crownassembling machine, the marginal ring or outer seal ring, as the casemay be, may be angular at its top and bottom as illustrated in FIGS. 5,7, 8 and 10 where crown assembling is carried out in machines wherestacking is not ernployed. It will be clearly recognized from a study ofFIG. 14, that the flat surfaces 21 and 22 of the preferred form of myinvention, as well as the flat surfaces of the other forms asillustrated in FIGS. 6, 9, 11, 12 and 13 facilitate the stacking of thesealing means and prevent nesting in a conventional crown assemblingmachine utilizing stacking, schematically illustrated in part in FIG.14.

It can be appreciated that with the large number of crown sealing meansbeing used, any saving of material is important. To accomplish thissaving in the sealing means itself, the sides of the marginal ring, suchas 21d and 21e, are curved or concave as illustrated in FIG. 12, or theHex-ring itself is pointed or concave as illustrated at 18a, 18h in FIG.15. This feature has the additional advantage of increased retentivitycharacteristics in the crown cap as can be appreciated from a study ofFIG. 3. As to the crown cap itself, the saving is accomplished by thereduction in the thickness of my sealing means as compressed (see FIG.4) as compared to conventional cork seals or other plastic seals so thatthe distance from the top of the cap to the locking ring 27 is reduced.Also, I have found with my seal, that thinner gage metal may be usedbecause of the reduced internal bottle pressure acting against thereduced area on my seal and crown. This reduction in area also permitsthe use of aluminum instead of tin-plate for the cap.

More specifically, in connection with the operation of my sealing means,in production runs it has been eX- perienced that plastic sealing meanswith annular seal rings tend to nest when seals are stacked in the feedtube of conventional crown assembling machines, i.e., the marginal rimsand sealing rings tend to overlap. This results in tearing of thesealing means by a shuttle or ejector and/or causes the shuttle toinsert more than one seal into any one crown. By the particularconfiguration of my invention, such nesting is overcome due particularlyto the preferred form of marginal seal rings, as illustrated in FIGS. 2,6, 9, 11, 12 and 13, where one seal ring is thicker than the other asthe case may be, and terminates on both sides by flats, such as 21 and22, or 13a, 13b. As a further aid to prevent nesting it is preferredthat the feed tube, indicated schematically in its entirety in FIG. 14as 31, and cylindrical section 32 thereof, conventionally designed forfeeding cork seals (and customarily has a larger inside diameter thanthe outside diameter of plastic sealing means), be provided with anintermediate tapering section 33, which connects the large section 32 toa smaller cylindrical section 34 of the feed tube. The section 34, beingof a smaller inner diameter than the inner diameter of the tube 32, isonly slightly larger, and preferably not more than .010 inch larger,than the outside diameter of the seal. In this manner the sealing meansline up and stack automatically, as illustrated in this FIG. 14, and theentire assembly is connected to a vibrator (not shown).

In the conventional crown assembling machine, there is provided ashuttle 35 or ejector, in connection to a source of motivating power(not shown) whereby the shuttle is reciprocated to the right and to theleft, as illustrated in FIG. 14, in and out of apertures 36 and 37 inthe cylinder 34 whereby the shuttle 35 may eject one sealing means at atime. I have improved the conventional crowning assembly machines stillfurther, by providing the shuttle 35 with a V-shaped portion 38 and achamfer 40. The V-shaped section 38 conforms, as can be seen, to theouter periphery of the marginal ring to aid in centering the periphery24 in the ejector and guiding it out of the feed tube and the chamfer 40prevents its catching or the like with the next sealing means above andin line to be ejected. I have found also in connection with thisoperation that by providing the sealing rings with the llattest inclinedsurfaces such as 15 and 17, facing outwardly, the ejection mechanism 35functions more successfully.

As hereinbefore mentioned, it is highly desirable that the plasticsealing means be retained in the crown cap prior to the crowningoperation. To augment this, I have provided my sealing means with apointed or narrow rimmed portion 24 or 24', for the purpose ofincreasing the specific pressure of the seal against the crown skirtwhich together with the flex-ring provides the required frictionalretentivity to retain the seal in the crown cap. However, in certainapplications, it is desirable to insure that the plastic sealing meanswill remain positively in the crown cap prior to the crowning operationand I have found that my sealing means cooperates exceedingly well withdimples or indentations 41, (see FIGS. 3 and 4). These indentations areusually spaced equidistant about the cap and formed in the metal of thecap slightly below the curved portion 42 and a sufficient distance belowthe top of the crown cap to permit the sealing means to assume acurvature as illustrated in FIG. 3. The sealing means 10, being oversizeand with a pointed rim 24 or 24', will snap over the dimples in the capwhen so inserted and brace itself against the top portion of the dimples41 and thereby be positively retained in the crown cap.

As hereinbefore mentioned, one embodiment of my crown cap comprises acap 23 having an improved sealing retaining means therein. Thus, asillustrated in FIG. 16, the dimples 41 may be replaced by a continuousinward protruding rim 43, formed in the metal of the cap itself. Themarginal rim 43 will have the same function and operation as the dimples41 and in a crown may be located in substantially the same location withrespect to the top as the dimples.

As another feature of my invention, the known dimples 41, such asillustrated in FIG. 3, or the improved rim 43, such as illustrated inFIG. 16, may be replaced with a plurality of small projections or dots44 formed of a special lacquer in such a manner as illustrated in FIG.18 or by a perpheral rim 45, such as illustrated in FIG. 17. Theformation of these lacquer dots and rims will be explained in moredetail hereinafter but it is sufficient to say that the lacquer dots 44and lacquer rim 45 will function to retain the seals in the crown cap23.

In accordance with conventional practice the tinplate on the side, whichwill become the inside of the nished crown cap is coated with a lacquercomposed of an oleoresinous type of a drying oil and a varnish resintogether with a dryer and gold or other color material. This lacquerdries with a glossy surface and usually provides a minimum of friction.As heretofore mentioned, to increase the frictional characteristic ofthe conventional lacquer and thereby the retentivity of the seal in thecrown, I add a small amount of inert material (3%-5%) such as bentonite,magnesium silicate, etc., to the lacquer for the first coating. Ifpreferred, means may be provided to produce brush marks or a texture tothe coating, so as to roughen the surface covering the skirt, to improvethe frictional retentivity of the crown still further.

Turning now to FIG. 19 wherein I have illustrated a flat sheet oftin-plate 46 used in the conventional crown making operation, after theconventional lacquer has been applied to the tin-plate by 4the coatingmachine and has dried.

This improved lacquer, as described above and indicated in FIGS. 17, 18and 19 may be applied either as concentric rings 45 as illustrated or asplurality of dots 44, which are relatively thin, yet in the finishedproduct as illustrated in FIGS. 17 and 18 provide sufficient frictionalsurface to considerably improve the retention of the sealing meanstherein. These rings 45 or dots 44 are applied after the first coatingof lacquer has dried and can be carried out by running the tin platethrough a second coating machine or may be applied after the blankingout of the crown by a spray process or brushing process or any other`suitable means.

Where it is not necessary or desirable to provide dots or rims asillustrated, -this same modified lacquer may be applied as a rst coatingthe same as present practice of conventional lacquer by the conventionalmachine and, if preferred, an attachment may be provided to producebrush marks or a texture to the coating to improve the frictionalretentiveness of the crown still further.

It may be desirable, where thought to be necessary, that a liquidadhesive be applied into the formed crown to retain the seal. Thisadhesive may comprise a blend of synthetic rubbers and modifyingresinous material dissolved in a volatile solvent such as hexane. Thisadhesive could be applied to the crown inside thereof in the crownassemblying process in a customary manner with a rotary applicator orany other suitable means as is conventional before the seal is inserted.Thus, as in conventional crown assembly operations, when the crown isheated to a temperature of about 230 F. the `solvent will be evaporated.In Vsuch an operation cam-controlled plungers of the conventional crown.assembly machine such as illustrated at 50, but having a reduced endportion 51 may be used to press the center membrane or diaphragm of thesealing means against the crown top heated by contact with the heatedtable 52 bringing about a thermo-plastically produced deformation andalignment `of the center seal diaphragm with the crown top therebyaiding the spreading the adhesive between the `seal and the crown andconsequently accelerating the evaporation of the solvent and resultingin a secure bond, The reduced end portion 51 -of the plungeraccommodates the sealing rings and/ or sealing marginal rim as can beappreciated.

Where herein the various parts of my invention have been referred to aslocated in a right -or left or an upper or lower or an .inward oroutward position, it will be understod that this is done solely for thepurpose of facilitating description and that such references relate onlyto the relative positions of the parts as shown in the drawings.

Also, it is to be understood 4that many changes and modifications may bemade without departing from the scope or spirit of the invention and theinvention is dened and comprehended solely by the appended claims whichshould be construed as broadly as the prior art will permit.

I claim:

1. A new and improved crown cap for pressure containers and the likecomprising a shell having an internally domed circular portion with asmooth internal surface bounded by a top corner radius portion of smoothcurvature and having a peripheral skirt portion joined to said topcorner radius and adapted for engagement with a locking ring of thecontainer, the improvement comprising means deiining an inwardlyextending peripheral band yof lacquer formed between said skirt portionand said corner radius portion, said band of lacquer engaging the edgeof a plastic closure sealing means for positive retention of saidsealing means in said crown cap prior to the crown capping operation.

2. A new and improved crown cap for pressure containers and the likecomprising a shell having an internally domed circular portion with asmooth internal surface bounded by a top corner radius portion of smoothcurvature and having a peripheral skirt portion joined to said topcorner radius and adapted for engagement with a locking ring of thecontainer, the improvement comprising means defining an inwardlyextending frictional retentive means formed by lacquer between saidskirt portion and said corner radius portion and, said retentive meansengaging the edge of a plastic closure sealing means for frictionalretention of said `sealing means in said crown cap prior to the crowncapping operation.

3. A new and improved crown cap for pressure containers and the likecomprising a shell having an internally domed circular portion with asmooth internal surface bounded by a top corner radius portion of smoothcurvature and having a peripheral skirt portion joined to said topcorner radius and adapted for engagement with a locking ring of thecontainer, the improvement comprising means dening a plurality ofinwardly extending dots of lacquer formed between said skirt portion andsaid corner radius portion, said dots of lacquer engaging the edge of aplastic closure sealing means for positive retention of said sealingmeans in said crown cap prior to the crown capping operation.

References Cited by the Examiner UNITED STATES PATENTS 1,512,347 10/24Lorenz 215-40 2,092,192 9/37 Von Till 21S-43 2,858,659 11/58 West 53-2872,904,837 9/59 Crabbe 21S-43 2,948,096 8/ 60 Anderson 53-287 3,033,4075/62 Isele Aregger 215-39 3,089,604 5/63 Golde et al 215-39 JOSEPH R.LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

1. A NEW AND IMPROVED CROWN CAP FOR PRESSURE CONTAINERS AND THE LIKE COMPRISING A SHELL HAVING AN INTERNALLY DOMED CIRCULAR PORTION WITH A SMOOTH INTERNAL SURFACE BOUNDED BY A STOP CORNER RADIUS PORTION OF SMOOTH CURVATURE AND HAVING A PERIPHERAL SKIRT PORTION JOINED TO SAID TOP CORNER RADIUS AND ADAPTED FOR ENGAGEMENT WITH A LOCKING RING OF THE CONTAINER, THE IMPROVEMENT COMPRISING MEANS DEFINING AN INWARDLY EXTENDING PERIPHERAL 